#!/usr/bin/env bash

set -eu

script_name=$0

die() {
    echo >&2 "$@"
    exit 1
}

about() {
    die "usage: ${script_name} [-q] <port_number>"
}

[[ $# -lt 1 ]] && about

QUIET=
if [[ "$1" == "-q" ]]; then
    QUIET=quiet
    shift
fi

[[ $# -lt 1 ]] && about

port_number=$1

# 4 seconds may seem long, but the tests must work on embedded, slow arm boxes too
for _ in $(seq 40); do
    nc -z localhost "${port_number}" >/dev/null 2>&1 && exit 0
    sleep .1
done

# send to &3 if open
if { true >&3; } 2>/dev/null; then
    [[ -z "${QUIET}" ]] && echo "Can't connect to port ${port_number}" >&3
else
    [[ -z "${QUIET}" ]] && echo "Can't connect to port ${port_number}" >&2
fi

exit 1